WO2014006092A1

WO2014006092A1 - Data recording device and method relating to a time shifting function on a recording medium

Info

Publication number: WO2014006092A1
Application number: PCT/EP2013/064033
Authority: WO
Inventors: Bruno Le Garjan; Vincent GENIEUX; André MAGRAS; Guillaume Burguiere; Arnaud Menard; Brieuc THOMAS; Michel Auffray; Viviane BESSON
Original assignee: Thomson Licensing
Priority date: 2012-07-03
Filing date: 2013-07-03
Publication date: 2014-01-09
Also published as: JP2015526007A; US20150156450A1; CN104521241A; EP2870773B1; KR20150029007A; EP2870773A1; US9641792B2

Abstract

The invention relates to a device and a method for recording data on a recording medium. The invention relates to the implementation of the time shifting function in a part of said recording medium called the time shifting buffer memory having a size defined in terms of recording capacity. For the time shifting buffer memory, a first threshold defines a capacity limit, a second threshold defines a recording time limit. The device records the data in the time shifting buffer memory as long as the second threshold is not attained and when the second threshold is attained before the first threshold, the processor truncates the start of the time shifting buffer memory when the data currently being read are not situated at the start of the buffer memory or switches back to the reading of the data of the time shifting buffer memory when the data currently being read are situated at the start of the time shifting buffer memory.

Description

The invention relates to a device and a method for recording data on a recording medium implementing a time shift function. BACKGROUND OF THE INVENTION The invention relates to a device and a method for recording data on a recording medium implementing a time shift function.

The present invention relates to a method and a device for delayed playback of digital video data. This function is also called the time shift function ("timeshift").

Video documents encoded as digital data offer many processing possibilities.

The invention more particularly relates to the delayed reading of data recorded on a recording medium, which consists in recording a program on a recording medium in a file, several files or any zone, while simultaneously reading this program with a some delay. This application allows the user to pause the replay of the program when desired and to resume where it left off.

Known devices, including devices of the digital television decoder type, making it possible to implement delayed playback methods have many disadvantages.

Among these known devices, some provide methods in which the amount of storage resources that can be allocated to a file other than the delayed replay file depends on the other applications made by the device. This causes many disadvantages:

On the one hand, the delayed read file can no longer have new resources to continue storing data.

On the other hand, the storage capacity allocated to the delayed reading method is not controlled, it is possible that this method occupies too much storage data of the decoder, thus generating malfunctions of the latter, for example for Perform other applications that can not access required storage capacity. Moreover, when the delayed reading method is used simultaneously with other applications requiring data storage, the management of the storage space allocated to each application is complex and difficult. This problem is all the more noticeable when the storage capacity is reduced and this is the case when the decoders only have memories of RAM type (acronym for "Random access memory") or flash of more limited capacity than that of hard disks. .

When the time shift buffer is full, the start of the time shift buffer is truncated and space is freed to record the sequence of received data. It can be seen that if the user reads the data with a large offset from their write in the time shift buffer, the read pointer is at the beginning of the time shift buffer, it is quite possible that the new Data received overwrites data that has not been read or can not be written. In this case, the read pointer must jump into the buffer, which gives a very disturbed read for the user since the display of data jumps over time.

This phenomenon is accentuated when the data rates received vary over time and increase. Broadcasters often broadcast TV channels at varying rates. Since the same string does not have a constant bit rate, it is difficult to predict the capacity of the buffer memory necessary to adapt to these flow fluctuations and precisely to avoid too many jumps in time, due to truncations of the buffer memory. .

It is therefore important to set the buffer so as to avoid such jumps over time or at least to reduce them.

A first invention provides a device for receiving and recording data on a recording medium, the apparatus comprising a processor for implementing a time shift function in a part of the recording medium called a time shift buffer, characterized in what he understands Means for defining a first threshold defining a capacity limit of the time shift buffer memory and

Means for defining a second threshold defining a recording time limit in the time shift buffer memory and

The processor stores the data in the time offset buffer until the second threshold is reached and when the second threshold is reached before the first threshold, the processor truncates the start of the time offset buffer when the data during playback are not located at the beginning of the buffer or replay reads data from the time shift buffer when the data being read is located at the beginning of the time shift buffer.

Advantageously, the processor comprises

means for analyzing, at each reception of a data channel, at least the average rate of each channel,

means for adjusting the second threshold as a function of the at least average flow rate. Advantageously, the means for analyzing the average flow rate also analyze the maximum flow rate of each channel, the means for adjusting the limit in recording time then adjusting the limit as a function of the mean flow rate and the maximum flow rate of each channel.

Advantageously, the limit in recording time is adjusted for each channel as a function of its average rate.

Advantageously, the capacity is adjusted for each channel according to its average flow rate and its maximum flow rate.

Preferably, the processor comprises

means for analyzing the type of data received,

means for adjusting the second threshold according to the type of data received.

Preferably, the type comprises:

- audio data,

- standard definition video data,

- High definition video data.

Advantageously, the processor comprises Means for detecting a filling threshold of the buffer memory.

Advantageously, the processor comprises means for transcribing the received data when the filling threshold is crossed.

Advantageously, the processor comprises means for detecting the type of data received.

Advantageously, the processor comprises means for transcribing the data received when the data type corresponds to data of the high-speed type.

Advantageously, the processor comprises

means for detecting the data relating to the language displayed by the user or to the subtitling watched by the user, when the filling threshold is crossed,

Means for recording in the temporal shift buffer memory only the detected data.

Advantageously, the processor comprises means for detecting the data relating to the language displayed by the user or to the subtitling watched by the user, and means of not recording in the temporal shift buffer memory the data detected when the data type corresponds to data of the broadband type.

Advantageously, the processor comprises means for recording in the time shift buffer memory only a percentage less than the totality of the groups of data received when the received data are coded in data group when the threshold of filling is crossed. Advantageously, the processor comprises means for recording in the time shift buffer memory only a percentage less than the totality of the data groups received when the received data are coded in a data group when the data type corresponds to data of type broadband.

The first invention also relates to a method for receiving and recording data on a recording medium, in a device comprising a processor for implementing a time shift function in a part of said recording medium called time shift buffer. According to the invention, the method comprises:

Determining a first threshold defining a capacity limit of the time shift buffer memory and

Determining a second threshold defining a recording time limit in the time shift buffer memory and

Storing the data in the time shift buffer until the second threshold is reached and

when the second threshold is reached before the first threshold, truncating the start of the time shift buffer when the data being read is not located at the beginning of the buffer memory or

transition to the read mode of the data of the time shift buffer memory when the data being read is located at the beginning of the time shift buffer memory.

A second invention relates to a device for receiving and recording data on a recording medium, the device comprising a processor for implementing a time shift function in a part of said recording medium called a time shift buffer having a size defined in terms of recording capacity. According to the invention, the processor comprises:

Means for defining a first threshold defining a capacity limit of the time shift buffer memory and

means for defining a third threshold defining a minimum limit in recording time in the time shift buffer memory

the processor stores the data in the time shift buffer as long as at least one of the first threshold or the second threshold is not reached and when at least one of the two thresholds is reached:

if the third threshold is also reached, then

o if the processor read pointer is in an area of the time shift buffer in which the processor has to truncate data, the processor reverts to the normal read mode of the time shift buffer if pause was enabled or if the playback speed was lower than the normal playback speed, and

o If the processor read pointer is not in an area of the time offset buffer in which the processor has to truncate data, then the processor truncates data in the time shift buffer.

Preferably, when the processor is replayed in normal-speed playback mode, then if the filling threshold reaches the size defined in terms of recording capacity, the processor performs a jump to the reading pointer.

Preferably, the processor comprises means for defining the type of data received and means for defining the three thresholds as a function of the type of data received.

Preferably, the data type is selected from the audio type, high definition video or standard definition video.

Preferably, the data type is selected from a type of coding in which the data is coded, and preferably when the data is video data, of the MPEG-2 type or the H-264 type.

Preferably, the processor comprises

means for defining the value of the three thresholds as a function of the average flow rate of each channel, for each channel received.

Preferably, the means for analyzing the average flow rate also analyze the maximum flow rate of each channel and the means for defining the value of the three thresholds define the values of each threshold as a function of the average flow rate and the maximum flow rate of each channel.

Preferably, the device comprises

means for determining that the time shift buffer memory has reached a so-called critical threshold filling threshold.

According to one embodiment of the invention, the device comprises means for transcribing the received data. According to one embodiment of the invention, the means for transcoding the received data transcode the received data only when the critical threshold is reached.

According to an embodiment of this second invention, the device comprises means of not recording in the time shift buffer memory, a percentage of the groups of data received, when the received data are coded in data group.

According to one embodiment of the invention, the means of recording in the time shift buffer memory only a percentage of the data groups received do so only when the critical threshold is reached.

According to one embodiment of the invention, the data being coded in a plurality of modes, the modes being relative to an audio language or to a subtitling, it comprises

means for detecting the mode in which the data are decoded,

means for recording in the buffer the data only in the decoded mode.

According to one embodiment of the invention, the means of recording in the buffer memory the data only in the decoded mode do so only when the critical threshold is reached.

The second invention further relates to a method for receiving and recording data on a recording medium in a device comprising a processor for implementing a time shift function in a part of the recording medium called a time shift buffer. having a defined size in terms of recording capacity; the process comprises

a determination of a first threshold defining a capacity limit of the time shift buffer memory and

a determination of a second threshold defining a limit in recording time in the time shift buffer memory and

a determination of a third threshold defining a minimum limit in recording time in the time shift buffer memory the recording of the data in the temporal shift buffer memory as long as at least one of the first threshold or the second threshold is not reached and when at least one of the two thresholds is reached:

- if the third threshold is also reached, then

o if the read pointer of the processor is in an area of the time offset buffer in which the processor has to truncate data, switch to normal playback mode of the time shift buffer if the pause mode was activated or if the reading speed was below normal reading speed, and

o If the processor read pointer is not in an area of the time offset buffer in which the processor has to truncate data, then truncation of the data in the time shift buffer.

A third invention relates to a device for receiving and recording data on a recording medium, the device comprising a processor for implementing a time shift function in a part of the recording medium called a time shift buffer memory. According to the invention, the device comprises means for detecting the type of data received, and means for adjusting a limit in recording time in the time shift buffer memory according to the type of data received.

Preferably, the data type may be selected from audio type data, high definition video type data and standard definition type data.

Preferably, the data comprises an identifier indicating the type of data, the detection means then reading the type in the received data.

Preferably, the data is coded in the MPEG-2 TS format, the identifier then being the PMT field.

Preferably, the device comprises means for adjusting a size limit defining a capacity of the temporal shift buffer memory, as a function of at least said type of received data.

Preferentially, the means of adjusting a time limit also adjust a minimum time limit ensuring a time recording in the time shift buffer whatever the maximum rate of the data received, according to at least said type of data received.

Advantageously, the device according to this third invention comprises means for transcribing the received data prior to their recording in the time shift buffer memory.

Advantageously, the data being coded in a plurality of modes, the modes being relative to an audio language or to a subtitle the processor comprises means for detecting the mode in which the data is decoded, and means for recording in the time shift buffer, the data only in the only decoded mode.

Preferably, the data being audio video data encoded into video data groups and data group, the device includes means for recording in the buffer only a percentage less than the totality of the received video data group and all groups of audio data.

Preferably, the means for transcoding the data received prior to their recording in the time shift buffer transcode the data only when the filling of the time shift buffer memory is greater than a first threshold or when the data rate of the received data is greater than first. threshold.

According to a preferred embodiment of this third invention, the means for recording in the time shift buffer memory, the data only in the only decoded mode do so only when the filling of the time shift buffer memory is greater than a first threshold or when the data rate received is greater than the first threshold.

This third invention also relates to a method for receiving and recording data on a recording medium, in a device comprising a processor for implementing a time shift function in a part of said recording medium called a time shift buffer, characterized in that it comprises the steps of:

detection of the type of data received, adjusting a recording time limit in the time shift buffer according to said received data type.

A fourth invention relates to a device for receiving and recording data on a recording medium, the device comprising a processor for implementing a time shift function in a part of the recording medium called a time shift buffer memory; the processor comprising:

means for initializing the buffer memory so as to make its recording time capacity equal to a fixed threshold,

means for adjusting the recording time capacity of the buffer memory to a value greater than the threshold value as a function of the at least average bit rate.

According to an embodiment of the fourth invention, the means for analyzing the average flow rate also analyze the maximum flow rate of each channel, the means of adjusting the capacity in recording time then adjusting the capacity as a function of the average flow rate and the maximum throughput of each channel.

According to an embodiment of the fourth invention, the capacity is adjusted for each channel according to its average rate.

According to an embodiment of the fourth invention, the capacity is adjusted for each channel according to its average flow rate and its maximum flow rate.

According to an embodiment of the fourth invention, the device comprises means for adjusting a size limit (BSB) defining a capacity of the time shift buffer memory as a function of at least the average bit rate. According to an embodiment of the fourth invention, the means for adjusting a size limit defining a capacity of the time shift buffer as a function of at least the average rate further adjusts the size as a function of the maximum bit rate.

According to an embodiment of the fourth invention, the means for adjusting a time limit also adjusts a minimum time limit (MBSS) guaranteeing a recording time in the shift buffer. regardless of the maximum data rate received, based on at least the average bit rate.

According to an embodiment of the fourth invention, the minimum time limit is adjusted according to the average rate and the maximum rate.

According to an embodiment of the fourth invention, the device comprises means for transcribing the data received prior to their recording in the time shift buffer memory.

According to an embodiment of the fourth invention, the data is coded in a plurality of modes, the modes being relative to an audio language or a subtitle, the processor comprises:

means for detecting the mode in which the data are decoded,

means for recording in the time shift buffer memory, the data only in the only decoded mode.

According to an embodiment of the fourth invention, the data is audio video data coded in groups of video data and audio data group, it comprises means for recording in the buffer memory only a percentage less than the totality Received video data groups and all audio data groups.

According to an embodiment of the fourth invention, the means for transcoding the data received prior to their recording in the time shift buffer transcode the data only when the filling of the time shift buffer memory is greater than a first threshold or when the data rate received is greater than the first threshold.

According to an embodiment of the fourth invention, the means for recording in the time shift buffer memory, the data only in the only decoded mode do so only when the filling of the time shift buffer is greater than a first threshold or when the received data rate is greater than the first threshold.

The fourth invention also relates to a method for receiving and recording data on a recording medium, in a device comprising a processor for implementing a function of temporal offset in a portion of the recording medium called a time shift buffer, the method comprising the steps of:

- initializing the buffer so as to make its recording time capacity equal to a fixed threshold,

- analysis, at each reception of a data channel, at least the average rate of each channel,

- Adjusting the capacity of the buffer storage time to a value greater than the threshold value according to the at least average rate.

A fifth invention relates to a device for receiving and recording audio video data on a recording medium, the device comprising a processor for implementing a time shift function in a part of the recording medium called a time shift buffer, the data being coded in different modes. According to the invention the processor includes means for transcoding the received data to reduce the amount of data to be recorded before recording in the time shift buffer.

Advantageously, the latter device comprises means for detecting that the buffer has reached a filling rate higher than a first predetermined threshold value.

Advantageously, the means for transcoding the received data only transcode the received data when the first threshold value is exceeded.

Advantageously, the latter device comprises means for detecting the bit rate of the data received.

Advantageously, the means for transcoding the received data transcoding the data received only when the bit rate is greater than a determined bit rate.

Advantageously, the latter device comprises means for detecting the selected audio language and subtitles and for recording in the time shift buffer only the data in the selected audio language and the selected subtitles. Advantageously, the means for detecting the audio language and the selected subtitles record in the time shift buffer only the data in the selected audio language and the selected subtitles when the time shift buffer has reached a desired time. second threshold value at least equal to the first threshold value.

Advantageously, the means for detecting the audio language and the selected subtitles record in the time shift buffer only the data in the selected audio language and the selected subtitles when the bit rate is greater than a second determined bit rate. the second flow being greater than the first flow.

Advantageously, the received data is encoded in data group, the device further comprises means for only recording part of the data groups in the time shift buffer memory.

Preferably, the means of only recording part of the groups of data in the time shift buffer store only part of the data groups when the filling of the time shift buffer has reached a third value. threshold at least equal to the second threshold value.

According to one embodiment of the invention, the means for only recording part of the data groups in the time shift buffer store only part of the data groups when the bit rate is greater than one. second determined rate, the second rate being greater than the first rate.

According to an embodiment of the present invention, the data is audio video data, it comprises means for detecting a field in the data relating at least to the coding rate, means for modifying the field according to the transcoding and means associating the modified field value with a time position in the data, the temporal position being relative to the time at which the data began to be transcoded.

The fifth invention also relates to a method for receiving and recording audio video data on a recording medium, in a device comprising a processor for implementing a time shift function in a part of the recording medium called time shift buffer, the data being encoded in different modes; the method comprising a step of transcoding the received data to reduce the amount of data to be recorded before recording in the time shift buffer.

A sixth invention relates to a device for receiving and recording audio video data on a recording medium, the device comprising a processor for implementing a time shift function in a part of the recording medium called a time shift buffer memory, the data being coded in a plurality of modes, the modes being relative to an audio language or to a subtitling. According to the invention, the processor comprises

means for detecting the mode in which the data are decoded,

According to an embodiment of this sixth invention, the means of not recording in the time shift buffer memory that the data in a single decoded mode are able to trigger the recording when the filling threshold of the buffer memory is greater than a first predetermined value.

According to an embodiment of this sixth invention, the means of not recording in the time shift buffer memory only the data in a single decoded mode are able to trigger the recording when the bit rate of the received data is greater than a predetermined value. .

According to an embodiment of this sixth invention, when the data is coded according to the MPEG-2 or MPEG-4 standard, the PMT tables associated with the data are modified prior to their recording.

According to an embodiment of this sixth invention, the processor further comprises:

means for detecting the filling rate of the time shift memory following the recording of the data in the only decoded mode,

means for recording, in the time shift buffer memory, only a part of the data groups received, when the data are coded in groups of data, when the filling ratio is greater than a second threshold greater than the first threshold.

means for detecting the filling rate of the time shift buffer memory after the recording of said data in the only decoded mode,

means for transcoding the data in the only mode decoded prior to their recording in the time shift buffer memory when the filling ratio is greater than a third threshold greater than said first threshold.

means for transcoding the part of the groups of data in the only decoded mode prior to their recording in the time shift buffer memory when the filling ratio is greater than a fourth threshold greater than said second threshold.

The sixth invention also relates to a method for receiving and recording audio video data on a recording medium, in a device comprising a processor for implementing a time shift function in a part of the recording medium called an offset buffer memory. time, the data being coded in a plurality of modes, the modes being relative to an audio language or to a subtitling characterized in that the method comprises

a step of detecting the mode in which the data are decoded,

a step of recording in the time shift buffer only the data in a single decoded mode.

A seventh invention relates to a device for receiving and recording data on a recording medium, the device comprising a processor for implementing a time shift function in a part of said recording medium called a time shift buffer, the data being audio video encoded in groups of video and audio data group data. According to the invention, the device comprises means for recording in the memory only a percentage less than the totality of the groups of video data received and all the groups of audio data.

According to an embodiment of this seventh invention, the means for recording in the memory only a percentage less than the totality of the groups of video data received and all groups of audio data, select a group of data on x groups of data. received data, where x is dependent on the bit rate of the received data.

According to an embodiment of this seventh invention, the device further comprises means for detecting that the buffer has reached a filling rate higher than a first predetermined threshold.

According to an embodiment of this seventh invention, the means of recording in the buffer memory only a percentage of the groups of video data record the percentage only if the filling of the buffer memory has reached the threshold.

According to an embodiment of this seventh invention, a percentage of the groups of video data is recorded, the percentage being proportional to the ratio between the read rate of the data in the buffer memory and the write rate of the data in the buffer memory. According to an embodiment of this seventh invention, the data being coded in a plurality of modes, the modes being relative to an audio language or to a subtitling, the processor comprises

means for detecting the mode in which the data are decoded,

According to an embodiment of this seventh invention, the means for recording in the temporal shift buffer memory only the data in a single decoded mode are able to trigger the recording when the filling threshold of the buffer memory is greater than a second threshold.

According to an embodiment of this seventh invention, the means of recording in the temporal shift buffer only the data in a single decoded mode are able to trigger the recording when the received data rate is greater than a predetermined value.

According to an embodiment of this seventh invention, the processor further comprises:

means for detecting the filling rate of the time shift buffer memory after recording a percentage of the video data groups,

means for transcoding the percentage of groups of data to be recorded prior to their recording in the time shift buffer memory when the filling ratio is greater than a third threshold greater than the first threshold.

means for transcoding the part of the groups of data in the only decoded mode prior to their recording in the time shift buffer memory when the filling ratio is greater than a fourth threshold greater than the second threshold.

The present invention also relates to a method for receiving and recording data on a recording medium, in a device comprising a processor for implementing a time shift function in a part of said recording medium called a time shift buffer, the data being audio video data encoded into video data groups and audio data group. According to the invention, the method comprises a step of recording in the memory only a percentage less than the totality of the groups of video data received and all the groups of audio data.

The inventions will be better understood and illustrated by means of examples of advantageous embodiments and implementations, which are in no way limitative, with reference to the appended figures in which: FIG. 1 represents a general diagram of an environment of use of a decoder according to a preferred embodiment of the proposed inventions, FIG. 2 represents a general diagram of a decoder according to a preferred embodiment of the proposed inventions,

FIG. 3 represents a first embodiment of the first invention,

FIG. 4 shows a second embodiment of the invention, in which parameters of the time shift buffer memory are adjusted according to at least one bit rate of the data received,

FIG. 5 represents a third embodiment of the invention, in which parameters of the time shift buffer memory are adjusted according to the type of data received,

FIGS. 6a and 6b represent a first example of a decrease in the rate applied to the data received,

FIGS. 7a and 7b show a second example of a decrease in the rate applied to the data received,

FIGS. 8a and 8b show a third example of a decrease in the rate applied to the data received.

FIG. 9 represents a preferred embodiment of the second invention,

- Figures 10 and 1 1 represent alternative embodiments of the inventions.

The represented modules are functional units, which may or may not correspond to physically distinguishable units. For example, these modules or some of them may be grouped into a single component, or be functionalities of the same software. On the other hand, some modules may be composed of separate physical entities.

Figures 1 and 2 are applicable to all the inventions described in this document.

FIG. 1 represents a system comprising reception devices 1, 2 3 also called digital decoders implementing the invention. Such devices can be connected to interfaces 4 which are also called gateways via a local area network 5 ethernet for example. A main role of the gateways is to connect the devices 1, 2 and 3 to one or more external networks. In FIG. 1, the gateway 4 is connected to an internet service provider (ISP) 6 via an ADSL network 13 (acronym of "asynchronous digital subscriber line"). The gateway 1 can also be connected to other types of networks.

The digital decoders 1, 2 and 3 can also be connected directly without going through a gateway to a program provider. They can be of the cable, satellite, multicast IP or other type and have their own means of reception, demodulation of signals received by cable or satellite channels.

The invention is therefore not limited to the illustration given to it in FIG. 1 where the decoders 1, 2, 3 are not connected directly to program providers but via a gateway 4.

Each decoder 1, 2, 3 can be respectively connected to a television

7, 8, 9. They can also be connected to computers or tablets or other mobile devices, for example equipped with a screen. In the case of a server client configuration, the time shift function is implemented on the server decoder and displayed on the client decoder (and possibly on the server decoder) or a companion device, for example a tablet or other device.

A remote control device, such as an infrared remote control, 10, 1 1, 12 respectively controls each decoder 1, 2, 3. These remote controls can also control the televisions 7, 8, 9.

FIG. 2 represents a preferred embodiment of a decoder according to the invention, in which only the functions of the decoder that are useful for understanding the invention are seen.

The decoder 3 comprises a processor 33 in charge of controlling the main functions of the decoder 3. It also comprises a memory 31 of the RAM type which can also be of flash type, magnetic disk, such as a hard disk, or optical disk or any other type . In this memory, a file 32 is allocated for managing a time shift function. By a file, we mean a file or a zone or partition carrying a System file for managing files. According to preferred embodiment of the invention, the size of this file is 1 GBytes.

A bus 35 allows data exchanges and checks between the different components of the decoder.

In nominal operation, the decoder 1 receives data from the gateway 4. The received data is recorded in the continuous time shift buffer memory. This allows, if the user presses a pause button on his remote control to stop the visualization of the channel he receives, to be able to read the data that he has not viewed during the pause later and thus delayed. A typical scenario is, for example, the reception of a telephone call by the user. He then presses pause to interrupt the visualization of the program he receives. After 5 minutes, he hangs up and wants to see what happened during the 5 minutes. It then resumes reading where it stopped by viewing the data contained in the time shift buffer. If it wishes, it can also catch the direct, by viewing the contents of the accelerated speed shift buffer, otherwise it can continue to view the contents of the time shift buffer and will always be late. 5mn compared to live. In general, it is possible to return a reverse until the user has changed channels.

However, the size of the time shift buffer is set at a maximum size (UBSB) set at 1 GBytes in the preferred embodiment.

Depending on the rate of the channel being received, the program time in 1 GB varies.

For a 12Mbit / s channel rate, the time shift buffer may contain approximately 1 minute of program time.

For an 8Mbit channel rate, the time shift buffer may contain approximately 16 minutes of program time.

For a 4Mbit channel rate, the time shift buffer may contain approximately 32 minutes of program time.

For a 2Mbit channel rate, the time shift buffer may contain approximately 64 minutes of program time. According to the prior art, when the temporal shift buffer memory is full or has reached a certain threshold in terms of filling ratio, the beginning (that is to say, one that is erased) is truncated and the new data received. The time shift buffer is represented by a fixed size file and not a circular buffer, in the preferred embodiment. So we do not necessarily rewrite the erased cells but we keep the file size constant, in bytes.

In other embodiments, the time shift buffer may be of circular buffer type. In any case, the time shift memory can be viewed as a circular type of memory from a logical point of view.

With the data relating to the different data rates, given above, it can therefore be seen that, based on a fixed time offset buffer size, recording times which are completely different as a function of the channel rate are different. This can be inconvenient for the user who does not observe the same behavior for his decoder according to the rate of the received channel.

BSB is the fill threshold in bytes of the time shift buffer.

A second threshold defining a time limit called BSS is then defined according to a first embodiment of the invention. This limit defines a capacity in minutes of filling the time shift buffer memory, for example 15mn.

Figure 3 shows this first embodiment of the first invention.

According to this first embodiment of the invention, during a first step E1, a user turns on his decoder and selects a reception channel with his remote control. The received data is then viewed by the user on a television screen connected to the decoder (note that the decoder can be integrated into the television and constitute a single device). The data is also stored in the time shift buffer 32 as it is received, step E2. Advantageously, the processor 33 manages the fill rate of the time shift buffer 32 as follows.

As long as the threshold BSS is not reached, step E3, nor that the threshold BSB is not reached, step E4, the data continue to be recorded in the temporal storage buffer. If the threshold BSB is reached while the threshold BSS is not reached, then we go to step E5 which consists in jumping to the read pointer of the time shift buffer memory. The jump (in size or time), depends on several parameters, which can be considered acceptable by a user. It can be assumed that a jump corresponding to a few seconds, for example 20 to 30, may be a limit considered acceptable for a user. Step E5 is followed by step E6 during which the start of the time shift buffer memory is erased in order to be able to write other received data, the UBSB size remaining constant. The erased data can be erased to addresses other than the addresses where the new data is written.

Following step E6, we go back to step E2. During the steps E3 to E6, the data is continuously received and written to the time shift buffer memory, the threshold BSB being lower than the threshold UBSB.

When the threshold BSS is reached, step E3, and if the read pointer is at the beginning of the time shift buffer memory, step E7, then the processor forces the pause mode and the decoder switches to read at normal speed (speed 1), step E8. Of course, if the decoder was not in pause mode (or in fast return, or slow speed as the idle) but at a speed greater than 1, then it is left at this speed (for example in time 2 times, 4 ...). Then, if the filling ratio is close to the recording capacity limit of the time shift buffer memory, step E10, then the read pointer jumps forward a few seconds, step E1 1, as previously explained, when from step E5. If in step E7, the read pointer is not at the beginning of the time shift buffer, then the start of the time shift buffer is truncated, step E9. By beginning, we A number of addresses, depending on the input or fixed rate, are heard in proportion to the size of the memory.

Thus, the data can be truncated periodically. The processor maintains the fill rate below the BSS threshold by periodically testing the amount of data recorded in time.

By beginning of the memory, one can define different values. For example, the beginning of the memory comprises a percentage of the threshold BSS. If BSS is set to 15 minutes, then the start represents the first 5 minutes of the time shift buffer for example.

When the threshold BSB is reached before the threshold BSS, then the start of the received data is truncated in the time shift buffer memory and a time jump of the reading is made if the truncated area contains the reading position.

According to this first embodiment, the processor 33 defines the two thresholds BSB and BSS in a predetermined manner.

In a predetermined manner, the threshold BSB can be set to 90% of the total storage capacity (UBSB) of the time shift buffer memory, ie 900MB. It can also be set to the maximum storage value, ie 1 GB but in this case, there may be overflows of the time shift buffer.

In a predetermined manner, the threshold BSS can be set at 15 minutes.

According to another aspect of the invention, instead of defining the threshold BSS, it is possible to define instead a second threshold in size BSB2. Figure 3 applies in the same way by replacing the threshold BSS by the threshold BSB2. The advantage of defining this second threshold in size and not in time makes it possible to absorb flow variations all the time.

According to a second embodiment, the thresholds or one of the two can be determined dynamically and for example based on data related to the different channels, various examples of which are given later.

FIG. 4 illustrates a dynamic setting of the time shift buffer memory according to this second embodiment.

During a step S1, a user turns on his decoder and selects a reception channel with his remote control. When setting When energized, the parameters of the time shift buffer memory BSB and BSS are set to a size defined as minimum. This size is for example 1 GB for BSB and 15 minutes for BSS. These so-called minimum sizes can also be parameterized for each decoder or in the factory or by the user or according to the country of use of the decoder or the broadcast network on which the decoder is connected. The received data is then viewed by the user on a television screen connected to the decoder (note that the decoder can be integrated into the television and constitute a single device). The data is also stored in the time shift buffer 32 as it is received, step S2. Step S2 corresponds to steps E1 and E2, FIG.

In a step S3, the processor 33 analyzes the speed with which the time shift buffer is filled in order to analyze the bit rates of the received channel. The average rate and, incidentally, the maximum rate are data that make it possible to better parameterize the time shift buffer memory. This can be done when receiving each channel.

The processor 33 observes the rate of each channel, it can very well also observe the flow of several channels and average these channels, but in the latter case, the measurement is less reliable than channel by channel. Measuring on a set of channels may be of interest if the channels are recognized as fairly similar in terms of throughput. The bit rate can also be data retrieved for example on the internet in the case of IP channels rather than being calculated by the decoder internally. For cable or satellite broadcasts, the bit rate can also be recovered by the decoder, on a website if the decoder can retrieve them or on a site set up by the operator or indicated in a private field of the signaling, or PMT service, SDT or NIT for example.

Preferably, the processor 33 analyzes the bit rate of each channel and sets the time offset buffer 32 for each channel. The setting can be dynamically adjusted when viewing a channel or can be used at the next connection to this channel to set the starting threshold value instead of setting it to a minimum value. The threshold BSS is thus adjusted according to the average flow. However, if the channel has large flow variations, it is also interesting to adjust the BSS threshold as a function of the maximum flow rate of the channel.

If we consider that the variation of flow on a given network is 50%, the threshold BSS can be calculated as follows:

BSS = (UBSB - ((BitRateMoy ^* 1 .5) ^* durationBitRateMax)) / BitRateMoy

When the threshold depends on both average and maximum flow, the BSS threshold can be calculated as follows:

BSS = (UBSB - (BitRateMax ^* durationBitRateMax)) / BitRateMoy

According to another variant, the threshold BSB representing the capacity limit of the time shift buffer memory is also parameterized as a function of the average rate.

According to another variant, the threshold BSB is also parameterized as a function of the average flow rate and the maximum flow rate.

Step E3 described with reference to FIG. 3 then uses the threshold value defined as indicated above.

Advantageously, a rate reduction can be further combined with this embodiment and its variants. Indeed, if it is possible to reduce the bit rate, then the user can benefit from a limit in higher recording time or at least in the same time, it is possible to put more data received.

According to a first variant related to the bit rate reduction, a transcoding of the data is carried out during the reception of the data.

Figure 6a illustrates this variant. During step G1, a user turns on his decoder and selects a reception channel with his remote control. The received data is then viewed by the user on a television screen connected to the decoder. The data is also stored in the time shift buffer 32 as it is received. Step G1 corresponds to steps E1 and E2, FIG.

In a step G2, the decoder receives the PMT tables with the data and saves them in the memory 31. PMT tables are saved as metadata in a database of the memory 31 and are re-injected periodically to the replay. They may also be recorded with the data in the time shift buffer, but this requires modifying the PMT tables at replay for each repetition. When the time shift buffer reaches a predetermined fill threshold, step G3, the processor 33 decides to transcode the received data to reduce their rate before they are recorded in the time shift buffer. During a step G4, according to a first variant, the processor 33 then modifies the received PMT tables before recording them. The PMT tables are modified to reflect the new format of the data recorded and saved as metadata associated with a position in the data flow. The processor records as metadata the initial PMT associated with a valid start position and the modified PMT associated with the start position of the transcoded data. Similarly, the processor manages the PMT table versions so that during replay, it detects PMT changes due to transcoding and actual PMT changes in the stream.

For example, if the processor transcode the data between times Τ0 + Χ and T1 -Y, then, if the initial stream includes the following PMTs:

T0 PMT V2 .... T1 PMT V3

in the stream recorded and decoded we have the following PMTs:

TO PMT V2 .... Τ0 + Χ PMT V3 T1 -Y PMT V4 T1 PMY V5

At replay, the PMT table is injected periodically into the stream, for example every 100ms depending on the position. If the processor makes leaps in the stream, the processor injects the previous PMT the position reached. Any PMT transition is handled as a new version of PMT in the stream.

During the replay, there is a passage through a black screen or a freeze of the image, due to this transition. In order to limit this transition by a black screen or a freeze of the image, it is also possible, during an instantaneous course, to record both the initial data (not transcoded) and the transcoded data low bitrate so that when replaying it is possible to use two video decoders temporarily and switch from one decoder to the other. According to a second variant of this step G4, the PMT tables are not modified. For this purpose, the processor uses metadata associated with a position in the stream, the metadata containing all the information necessary to allow the initial data to be substituted by the low bit rate data. In the same way, it is possible to limit the black screens or freeze of the image by recording for a few seconds the transcoded and nontranscoded data and by generating the metadatas reflecting these transitions.

The data is transcoded during a step G5. As long as the time shift buffer contains data above a predetermined threshold, the received data is transcoded. This last threshold may be lower than the threshold that initiates the start of transcoding.

According to a variant shown in FIG. 6b, step G3 is replaced by a step G3 '. The other steps G1, G2, G4, G5 of the process shown in FIG. 6b are identical to the steps G1, G2, G4, G5 of the method of FIG. 6a.

During step G3 ', the processor decides to transcode not according to a filling threshold of the buffer memory but by determining the bit rate of the received data. When the rate is greater than a predetermined threshold rate, the processor 33 then decides to transcode the received data. By flow rate is meant here, either the average rate of the data received, or an estimated rate according to the data received as indicated above. If the data is audio, its bit rate is lower than the SD video data rate and the HD video data rate.

Figures 6a and 6b relate to the transcoding of data.

When such transcoding is used as described above, step G5 is then followed by step E3 described with reference to FIG. 3. The main advantage of transcoding is that threshold BSS is reached less rapidly than when data are not transcoded. The disadvantage is of course the decrease in the resolution or the quality of the data recorded in the time shift buffer.

According to a second variant related to the reduction of bit rate, a bit rate reduction can be applied by recording only certain parts of the data. Figures 7a and 7b illustrate such a variant. Indeed, when the received data is audio video data and subtitles, the data is sometimes received in different audio languages with also several choices of subtitles. However, the user rarely changes the language listened to during the program, nor the subtitling. It is therefore possible to reduce the data recorded in the time shift buffer by recording only the selected audio language data and selected subtitles. This is also valid for multiple videos.

During a step A1, the data are received by the decoder 3 and recorded in the time shift buffer memory. When the time shift buffer 32 reaches a predetermined fill threshold, in time, step A2, the processor detects the decoded language and the subtitles viewed, step A3. During an A4 step, the processor then records only the audio data and the subtitles being viewed and listened to.

In order to reflect the data as saved, ie modified, the PMT tables are modified when the modified data to which they refer are saved.

According to a variant shown in FIG. 7b, step A2 is replaced by a step A'2. The other steps A1, A3, A4 of the process shown in FIG. 7b are identical to the steps A1, A3, A4 of the method of FIG. 7a.

In step A'2, the processor decides not to record all audio video data streams and subtitles corresponding to the different languages, not according to a filling threshold of the buffer memory but by determining the bit rate. received data. When the bit rate is greater than a predetermined threshold rate, the processor 33 then decides to record only the data in the selected audio language and the selected subtitles. By flow rate is meant here, either the average rate of the data received, or an estimated rate according to the data received as indicated above. If the data is audio data, its bit rate is lower than the SD video data rate and the HD video data rate.

According to a variant of these FIGS. 7a and 7b, it is also possible to decide to record only the data visualized and listened to without even take the test of step A2. As soon as the data is decoded by the processor 33 in order to be viewed and listened to (by a user who has selected the language and the subtitles he wishes to display), the processor can decide to record only the corresponding data. at the choice of the user.

Figures 7a and 7b relate to partial recording of the data. When such transcoding is used as described above, step A4 is then followed by step E3 described with reference to FIG. 3. The main advantage being that the threshold BSS is reached less quickly than when the data are not not transcoded.

According to a third variant related to the reduction of the bit rate, the processor 33 only records a part of the received data groups. When the data conforms to MPEG encoding standards, for example MPEG-2 or MPEG-4, the data is encoded as image groups known by the acronym GOP (acronym for "Group Of Pictures").

Figures 8a and 8b illustrate this embodiment.

During a step H1, the data is received by the decoder 3 and recorded in the time shift buffer memory. Step H1 corresponds to steps E1 and E2, FIG. 3. When the time shift buffer 32 reaches a predetermined filling threshold, in time, step H2, the processor decides to record only a percentage of the data groups ( GOP) received, step H3.

The percentage of GOPs recorded varies according to the bit rate of the received data. If the rate is considered high speed, for example when HD data is received, then a high percentage of the GOPs is not recorded. For example, 3 GOPs out of 4 received are recorded. GOPs are delimited by the indexing of intra (I) type images or IDR images for data conforming to the MPEG4 coding standard. On the other hand, in order to have a correct sound, all the audio data is recorded. Thus, when reading the temporal storage buffer, the video data vary slowly (there are freezes of the image for the missing GOPs) but the sound and the subtitles are restored integrally. According to a variant shown in FIG. 8b, step H2 is replaced by a step H2 '. The other steps H1, H3 of the process shown in FIG. 8b are identical to the steps H1, H3 of the method of FIG. 8a.

During step H'2, the processor decides not to record all the

GOPs not based on a buffer fill threshold but by determining the bit rate of the received data. When the rate is greater than a predetermined threshold rate, the processor 33 then decides to record only a percentage of the GOPs. By flow rate is meant here, either the average rate of the data received, or an estimated rate according to the data received as indicated above. If the data is audio, its bit rate is lower than the SD video data rate and the HD video data rate. This variant generates a significant degradation of the data and is less relevant than the variant described with reference to FIG. 8a.

According to a variant of these FIGS. 8a and 8b, it is also possible to decide to record only a percentage of the GOPs without even having the test of step H2. As soon as the data is decoded by the processor 33 in order to be viewed and listened to, the processor may decide to record only a percentage of the GOPs as a function of the bit rate of the received data. This variant, however, causes significant degradation of all data.

Figures 8a and 8b relate to partial recording of the data. When such a rate reduction is used, step H4 is then followed by step E3 described with reference to FIG. 3. The main advantage being that the threshold BSS is reached less rapidly than when the data are recorded in screen.

According to a fourth variation-related variant, the processor 33 combines a transcoding-related rate reduction with a rate reduction related to a recording of user selected data (language and subtitling). Thus, in a first step, the processor 33 applies a rate reduction by transcoding the data received according to the steps described in FIG. 6a or 6b.

Following step G5 of FIG. 6a or 6b, steps A3 and A4 of FIG. 7a or 7b are carried out and the stream is then transcoded and then only the data corresponding to the selected audio language and selected subtitles are stored in the time shift buffer.

When such a combined rate reduction is used, step A4 is then followed by step E3 described with reference to FIG. 3. The main advantage is that threshold BSS is reached less quickly than when data is recorded. In totality.

According to a fifth variant related to the reduction of the rate, the processor 33 combines a reduction of flow related to the transcoding to a reduction of flow linked to a partial recording of the GOPs. Thus, in a first step, the processor 33 applies a rate reduction by transcoding the data received according to the steps described in FIG. 6a or 6b.

Following step G5 of FIG. 6a or 6b, step H3 of FIG. 8a or 8b is carried out and thus the stream is transcoded and only certain GOPs are recorded in the time shift buffer memory.

When such a combined rate reduction is used, the step H3 is then followed by the step E3 described with reference to FIG. 3. The main advantage being that the threshold BSS is reached less quickly than when the data are recorded. In totality.

According to a sixth variant related to the reduction of bit rate, the processor

33 combines a rate reduction related to the recording of data (languages and subtitles) selected by the user to a bit rate reduction related to a partial registration of GOPs. Thus, as a first step, the processor 33 applies a rate reduction by making a selection of the data actually selected by the user and not recording in the time shift buffer memory, the audio data and the non-subtitles. used according to the steps described in Figure 7a or 7b.

Following step A3 of FIG. 7a or 7b, step H3 of FIG. 8a or 8b is carried out and thus the flow rate of the flow is doubly reduced.

When such a combined rate reduction is used, the step H3 is then followed by the step E3 described with reference to FIG. 3. The main advantage being that the threshold BSS is reached less quickly than when the data are recorded. In totality. According to a seventh variant related to the bit rate reduction, the processor 33 combines a transcoding rate reduction with a rate reduction linked to the recording of the streams actually used and a recording of a percentage of the GOPs. Thus, in a first step, the processor 33 applies a rate reduction by transcoding the data received according to the steps described in FIG. 6a or 6b.

Then, the processor 33 applies a rate reduction by recording only the data actually used, in terms of language and in terms of subtitling according to the steps described in Figure 7a or 7b. Then the processor 33 then performs a third rate reduction by recording only a percentage of the GOPs according to the steps described in Figure 8a and 8b.

According to a third embodiment, the thresholds BSS and BSB or one of them are defined dynamically according to the type of data transmitted by the channel.

This third embodiment is described with reference to FIG.

During a step F1, a user turns on his decoder and selects a reception channel with his remote control. When powering up, the parameters of the time shift buffer, BSB and BSS, are set to a size defined as minimum. This size is for example 1 GB for BSB and 15 minutes for BSS. These so-called minimum sizes can also be parameterized for each decoder or in the factory or by the user or according to the country of use of the decoder. The received data is then viewed by the user on a television screen connected to the decoder (note that the decoder can be integrated into the television and constitute a single device). The data is also stored in the time shift buffer 32 as it is received.

During a step F2, the processor 33 determines the type of stream received. The flow can be determined by analyzing fields present in data. When the received stream is of the MPEG (Motion Picture Expert Group) type, the PMT tables present in the stream make it possible to determine the type of data contained in the stream.

Among the types of flow is meant for example but not in a limiting manner, an audio stream, an HD video stream (high definition), an SD video stream (standard definition). For each type of data, the maximum flow rate is known.

We compare then in a step F3, with the previously received stream, if the user has just changed channel. If the flow is not of the same type as the previous one, the processor then adjusts during a step F4 the parameters of the temporal shift buffer memory 32. The step F3 is optional, it is also possible not to make comparison with the previous flow and adjust the thresholds each time the user changes channel.

Among the parameters to be adjusted, there is the limit in recording time BSS, if the limit in capacity is fixed.

If the data type (or string type) is chosen from

- audio (a radio service for example),

- HD video, (an HD TV service for example),

the SD video, (an SD TV service for example),

One can also consider an HD audio service and an SD audio service.

If the data is audio data, then both thresholds are set with the following thresholds:

BSS = BSS_aud

BSB = BSB_aud

If the data is HD video data, then both thresholds are set with the following thresholds:

BSS_HD BSS =

BSB = BSB_HD

If the data is SD video data, then both thresholds are set with the following thresholds:

BSS = BSS_SD

BSB = BSB SD Among the parameters, one can also adjust the limit in UBSB recording capacity, if the time limit is set.

The thresholds thus defined are used during step E3 with reference to FIG.

In order to improve this third embodiment, it is possible according to a first variant to reduce the bit rate of the recorded data.

For this purpose, it is possible to perform a transcoding of the received data prior to their recording. For this purpose, the steps G1 to G5 appearing in FIGS. 6a and 6b and previously described, are carried out prior to the step E3 described with reference to FIG. E3.

In order to improve this third embodiment, according to a second variant related to the reduction of the bit rate, a bit rate reduction can be applied by recording only certain parts of the data.

It is possible to reduce the data recorded in the time shift buffer by recording only the audio data that is being listened to and viewed.

For this purpose, the steps A1 to A4 appearing in FIGS. 7a and 7b and previously described, are carried out before the step E3 described with reference to FIG.

According to a third variant related to the bit rate reduction, the processor

33 records only a portion of the received data groups. When the data conforms to the MPEG coding standards, for example MPEG-2 or MPEG-4, the data is encoded in the form of image groups known by the acronym GOP (acronym for "group of pictures").

For this purpose, the steps H1 to H3 appearing in FIGS. 8a and 8b and described above, are carried out prior to the step E3 described with reference to FIG.

According to a fourth variation-related variant, the processor 33 combines a transcoding-related rate reduction with a rate reduction related to a recording of user selected data (language and subtitling). Thus, in a first step, the processor 33 applies a rate reduction by transcoding the data received according to the steps described in FIG. 6a or 6b. Following step G5 of FIG. 6a or 6b, steps A3 and A4 of FIG. 7a or 7b are carried out and the stream is transcoded, then only the data corresponding to the language listened to and the subtitles displayed are recorded in FIG. time shift buffer.

Following step G5 of FIG. 6a or 6b, step H3 of FIG. 8a or 8b is carried out and thus the stream is transcoded, then certain GOPs are recorded in the time shift buffer memory.

According to a 6 ^th embodiment related to reduction in output, the processor 33 combines a reduction in flow associated with the data record (language and subtitles) selected by the user to a reduction in speed in relation to a part of the recording GOPs. Thus, as a first step, the processor 33 applies a rate reduction by making a selection of the data actually selected by the user and not recording in the time shift buffer memory, the audio data and the non-subtitles. used according to the steps described in Figure 7a or 7b.

Following step A3 of FIG. 7a or 7b, step H3 of FIG. 8a or 8b is performed and thus the flow rate of the flow is doubly reduced.

When such a combined rate reduction is used, step H3 is then followed by step E3 described with reference to FIG. the main reason being that the BSS threshold is reached less quickly than when the data are recorded in full.

According to a seventh variant related to the reduction of the bit rate, the processor 33 combines a transcoding rate reduction with a rate reduction related to the recording of the streams actually used and a recording of a percentage of the GOPs. Thus, in a first step, the processor 33 applies a rate reduction by transcoding the data received according to the steps described in FIG. 6a or 6b.

We will now describe the specificities of the second invention.

According to this invention, the processor comprises:

the processor records the data in the time shift buffer memory as long as at least one of the first threshold or the second threshold is not reached and when at least one of the two thresholds is reached:

- if the third threshold is also reached, then o if the processor read pointer is in an area of the time offset buffer in which the processor has to truncate data, the processor reverts to normal playback mode of the time shift buffer if the pause mode was activated or if the read speed was lower than the normal read speed, and o if the read pointer of the processor is not in an area of the time offset buffer in which the processor has to truncate data, then the processor truncates data in the time shift buffer.

Figure 9 shows a preferred embodiment of this second invention.

According to this first embodiment, the data begin to be received during a step T1 by the decoder. The step T1 marks the beginning of the reception of the data on a channel, thus for example the change of channel, but the data continues to be received throughout the following stages.

The data is recorded as it is received in the time shift buffer, step T2. Then, during a step T3, a test is performed on the filling rate of the buffer memory. If one of the two thresholds BSB or BSS is reached, then if MBSS is also reached, step T4, and if the reading pointer is in the zone to be truncated, step T5, the decoder stops the pause mode and goes to read data at speed 1, step T7. Of course, if the decoder was not in pause mode (or in fast return, or slow speed as the idle) but at a speed greater than 1, then it is left at this speed (for example in time 2 times, 4 ...).

Then, a test is performed, in a step T8, to see if the filling rate of the buffer is close to the maximum capacity UBSB. If so, then the read pointer jumps forward, step T9, and the data between the current value of the pointer read and the new value of the read pointer are not read.

The user sees a jump in the image, and this jump must be minimized to avoid visual disturbances of users. Thanks to the invention, such jumps happen infrequently. The length of the jump may depend on the data rate, the UBSB capacity, the position of the read pointer. The length of the jump can be measured in size or advantageously in time, for example 10 to 20 seconds.

If during step T8, the decoder is not close to the maximum capacity reached, then we go back to step T2, that is to say that we continue to receive the data while regularly testing the thresholds BSB and BSS, this delaying if necessary, step T10 being optional.

If during step T5, the read pointer is not in the area to be truncated, then we go to step T6 and truncate the beginning of the time shift buffer memory. The size of the truncation also depends on the bit rate, the position of the read pointer, the capacity

UBSB ... Following step T6, we go back to step T2, by performing a delay if necessary, step T10, before testing again the thresholds BSS or BSB.

FIGS. 10 and 11 describe a first variant of the embodiment described in FIG. 9.

In these two variants, intermediate steps between steps T1 and T2 of FIG. 9 make it possible to parameterize the three thresholds BSS, BSB and MBSS as a function of the type of data received.

FIG. 10 illustrates this variant in which the data type (or the type of string) is chosen from

- audio (a radio service for example),

- HD video, (an HD TV service for example),

the SD video, (an SD TV service for example),

One can also consider an HD audio service and an SD audio service.

During a test V1 between steps T1 and T2, that is to say when receiving data, following a change of string, the processor 33 determines the type of data received. This type can be determined for example by reading header fields or metadata. In the case coded in MPEG-2 or MPEG-4 format, the PMT tables make it possible to detect such a type of data. If the data is audio data, then the three thresholds are set with the following thresholds during a step V4:

BSS = BSS_aud

BSB = BSB_aud

MBSS = MBSS_aud

The audio data rate is low compared to the video data rate, whether SD or HD.

If the data is not audio data, then during a step

V2, the processor tests if the data is SD video data. If the data is SD video data, then the three thresholds are set with the following thresholds during a step V5:

BSS = BSS_SD

BSB = BSB_SD

MBSS = MBSS_SD

If the data is not SD video data, then in a step V3, the processor tests whether the data is HD video data. If the data is HD video data, then the three thresholds are set with the following thresholds during a V6 step:

BSS_HD BSS =

BSB = BSB_HD

MBSS = MBSS_HD

Following the parameterization of the thresholds, we then go to step T2.

FIG. 11 further illustrates this variant relating to the data type, but the determination of the data type is not based on the audio, SD video, HD video type, but on the type of coding used to code the data.

During a test W1 between steps T1 and T2, that is to say when receiving the data, following a change of chain, the processor 33 determines the type of data received. This type can be determined for example by reading header fields or metadata. In the case of data coded in MPEG-2 or MPEG-4 (H264) format, the PMT tables make it possible to detect such a type of data. If the data is data H264 then the three thresholds are parameterized with the following thresholds during a step V4:

BSS_HD BSS =

BSB = BSB_HD

MBSS = MBSS_HD

If the data is not H264 data, then during a W2 test, the processor checks if the data is MPEG-2 data. If the data is MPEG-2 data, then the three thresholds are set with the following values in step W5:

BSS = BSS_SD

BSB = BSB_SD

MBSS = MBSS_SD

If the data are not MPEG-2 data, following the test of step W2, then the data is for example audio data but can also be data of another type. During a step W6, the three thresholds are parameterized with the following values:

BSS = BSS_X

BSB = BSB_X

MBSS = MBSS_X

Following the steps W4, W5 or W6, the processor proceeds to step T2.

Of course, the type of coding is not limited to the MPEG-2 type or

H264 but can be any other type of data encoding, even an encoding other than a video encoding.

Fig. 12 shows a second variant of the preferred embodiment. In this second variant, intermediate steps between the steps T1 and T2 of FIG. 9 make it possible to parameterize the three thresholds BSS,

BSB and MBSS depending on the data rate received.

During a step Z1, following step T1, the processor determines the average bit rate of the received data. It analyzes the speed with which the time shift buffer is filled in order to analyze the bit rates of the received channel. The average rate and, incidentally, the maximum rate are data that make it possible to better parameterize the time shift buffer memory. This can be done when receiving each channel.

Maximum flow learning is not only at the moment of current zapping but also by cumulation of the flows calculated during the previous chain changes on this same service.

The processor 33 observes the rate of each channel, it can very well also observe the flow of several channels and average these channels, but in the latter case, the measurement is less reliable than channel by channel. Measuring over a set of channels may be of interest if the channels are recognized as fairly similar in terms of throughput. The bit rate can also be data retrieved for example on the internet in the case of IP channels rather than being calculated by the decoder internally. For cable or satellite broadcasts, the bit rate can also be recovered by the decoder, on a website if the decoder can retrieve them or on a site set up by the operator or indicated in a private field of the signaling, or PMT service, SDT or NIT for example.

The different thresholds BSS, BSB, MBSS are calculated according to the threshold during a step Z2.

Preferably, the processor 33 analyzes the bit rate of each channel and sets the time offset buffer 32 for each channel. The setting can be adjusted dynamically when viewing a channel or can be used when next connected to this channel.

BSS = (UBSB - ((BitRateMoy ^* 1 .5) ^* durationBitRateMax)) / BitRateMoy, where BitRateMoy is the average bit rate, BitRateMax is the maximum rate and durationBitRateMax is the time during which we want to be able to support the maximum rate without saturation (overflow) buffer) when maximum flow conditions occur from an average flow rate.

BSS = (UBSB - (BitRateMax ^* durationBitRateMax)) / BitRateMoy

Figures 13a and 13b show a fourth variant of the invention in which a rate reduction is applied to the data received by the decoder.

The steps of FIGS. 13a and 13b are identical. FIG. 13a illustrates a reduction in flow made upstream of the method illustrated in FIG. 3 relating to a reduction of bit rate by transcoding the data.

Following the beginning of the reception of the data, step T1 of FIG. 9, the data rate is evaluated, step L1, for example with reference to FIGS. 4,5 or 6 described previously or by the use of data retrieved from the network ( metadata or others). For high bit rate, it is possible to hear for example the data rate coded in HD. By low rate, we can hear the audio data rate. For SD data, a threshold can be set below which the bit rate is considered low.

If the throughput is considered high then the PMT tables included in the feed are modified and saved

The PMT tables are recorded as metadata in a database of the memory 31 and are re-injected periodically to the replay. They can also be recorded with the data in the time shift buffer but this requires modifying the PMT tables at replay for each repetition. The processor 33 then modifies the received PMT tables before recording them. The PMT tables are modified to reflect the new format of the data recorded and saved as metadata associated with a position in the data flow. The processor 33 records as metadata the initial PMT associated with a start of validity position and the modified PMT associated with the start position of the transcoded data. Similarly, the processor 33 manages the PMT table versions so that during replay, it correctly detects PMT changes due to transcoding and actual PMT changes in the stream.

For example, if the processor 33 transcode the data between the instants Τ0 + Χ and T1 -Y, then, if the initial stream comprises the following PMTs: T0 PMT V2 .... T1 PMT V3

in the stream recorded and decoded we have the following PMTs:

TO PMT V2 .... Τ0 + Χ PMT V3 T1 -Y PMT V4 T1 PMY V5

During the replay, there is a passage through a black screen or a freeze of the image, due to this transition. In order to limit this transition by a black screen or a freeze of the image, it is also possible, during an instantaneous course, to record both the initial data (not transcoded) and the transcoded data low bitrate so that when replaying it is possible to use two video decoders temporarily and switch from one decoder to the other.

According to a variant of this step, the PMT tables are not modified. For this purpose, the processor 33 uses metadata associated with a position in the stream, the metadata containing all the information necessary to enable the initial data to be substituted by the low bit rate data. In the same way, it is possible to limit the black screens or freeze of the image by recording for a few seconds the transcoded and nontranscoded data and by generating the metadatas reflecting these transitions.

The data is transcoded during a step L3 before being recorded in the time shift buffer memory during the step T2 described above.

FIG. 13b illustrates the transcoding as does FIG. 13a but when the transcoding is positioned not immediately at the channel change but between the steps T4 and T5. Since the steps are identical to those of FIG. 13a, they are not described again here.

According to a variant of FIGS. 13a and 13b, step L1 is optional and the transcoding can be performed all the time, without a flow condition.

FIGS. 14a and 14b describe a fifth variant of the invention in which a rate reduction is also applied to the data received, but according to this rate reduction, a partial recording of the data is carried out.

When the received data is audio video data and subtitles, the data is sometimes received in different audio languages with also several choices of subtitles. However, the user rarely changes the language listened to during the program, nor the subtitling. It is therefore possible to reduce the data recorded in the time shift buffer memory by recording only audio data heard and viewed. This is also valid for multiple videos.

When the data is considered as high speed, as described with reference to step L1 previously (step K1 is identical to step L1), during a step K2, the processor 33 detects the audio language selected by user and detects the subtitles viewed. During a step K3, the processor 33 saves in the time shift buffer memory only received data whose language corresponds to that selected and the subtitles chosen by the user.

Figure 14b illustrates the rate reduction as shown in Figure 8a but positioned not immediately at channel change but between steps T4 and T5. Since the steps are identical to those of FIG. 14a, they are not described again here.

According to a variant of FIGS. 14a and 14b, step K1 is optional and the reduction in flow rate can be carried out all the time, without any flow condition.

Figures 15a and 15b describe a sixth variant of the invention in which a rate reduction is also applied to the received data but according to this rate reduction, only a percentage of the GOPs is recorded.

When the data are considered as high speed, as described with reference to step L1 previously (step M1 is identical to step L1), during a step M2, the processor 33 decides to record only a percentage of video GOPs received.

The percentage of GOP recorded varies according to the data rate received. For example, 3 GOPs out of 4 received are recorded. GOPs are delimited by the indexing of intra (I) type images or IDR images for data conforming to the MPEG4 coding standard. On the other hand, in order to have a correct sound, all the audio data is recorded. Thus, when reading the temporal storage buffer, the video data vary slowly (there are freezes of the image for the missing GOPs) but the sound and the subtitles are restored integrally.

Figure 15b illustrates the partial GOP bit rate reduction as shown in Figure 15a but when the rate reduction is set not immediately at the channel change but between the T4 and T5 steps. Since the steps are identical to those of FIG. 15a, they are not described again here.

According to a variant of FIGS. 15a and 15b, the step M1 is optional and the recording of a percentage of the GOPs can be carried out all the time, without a flow condition.

Depending on the observed flow rate, it is also possible to combine the flow reductions between them, combining one, two or three flow reductions simultaneously as previously described.

We will now describe the specificities of the third invention.

The method according to the third invention consists in carrying out the steps F1 to F4 of FIG. 5 previously described.

According to a preferred embodiment, this third invention relates to a device for receiving and recording data on a recording medium, the device comprising a processor for implementing a time shift function in a part of said recording medium called a buffer memory. time lag. According to the invention, the device comprises:

received data type detecting means, and means for adjusting a recording time limit in the time shift buffer according to said received data type.

Advantageously, according to a first variant related to the bit rate reduction, a transcoding of the data is performed upon reception of the data.

Figures 6a and 6b described above illustrate this variant. Steps G4 and G5 can be performed before or after step F2. Advantageously, according to a second variant related to the reduction of bit rate, a bit rate reduction can be applied by recording only certain parts of the data. Figures 7a and 7b described above illustrate such a variant. Steps A3 and A4 can be performed before or after step F2.

Advantageously, according to a third variant related to the reduction of bit rate, the processor 33 only records a part of the received data groups. When the data conforms to MPEG encoding standards, for example MPEG-2 or MPEG-4, the data is encoded as image groups known by the acronym GOP (acronym for "Group Of Pictures").

Figures 8a and 8b previously described illustrate this embodiment. Step H3 can be performed before or after step F2.

Figure 3 previously described also represents a particular embodiment of this invention.

Figure 9 previously described also represents a particular embodiment of this invention.

We will now describe the specificities of the fourth invention.

The method according to the fourth invention consists in carrying out the steps of FIG.

According to a preferred embodiment, this fourth invention relates to a device for receiving and recording data on a recording medium, the device comprising a processor for implementing a time shift function in a part of the recording medium called a buffer memory. time lag; the processor comprising:

means for adjusting the recording time capacity of the buffer memory to a value greater than the threshold value as a function of the at least average bit rate. During a step S1, a user turns on his decoder and selects a reception channel with his remote control. When power is applied, the parameters of the BSB and BSS time shift buffer are set to a size defined as minimum. This size is for example 1 GB for BSB and 15 minutes for BSS. These so-called minimum sizes can also be parameterized for each decoder or in the factory or by the user or according to the country of use of the decoder or the broadcast network on which the decoder is connected. The received data is then viewed by the user on a television screen connected to the decoder (note that the decoder can be integrated into the television and constitute a single device). The data is also stored in the time shift buffer 32 as it is received, step S2.

The processor 33 observes the rate of each channel, it can very well also observe the flow of several channels and average these channels, but in the latter case, the measurement is less reliable than channel by channel. Measuring on a set of channels may be of interest if the channels are recognized as fairly similar in terms of throughput.

Preferably, the processor 33 analyzes the bit rate of each channel and sets the time offset buffer 32 for each channel. The setting can be dynamically adjusted when viewing a channel or can be used at the next connection to this channel to set the starting threshold value instead of setting it to a minimum value.

The threshold BSS is thus adjusted according to the average flow. However, if the channel has large flow variations, it is also interesting to adjust the BSS threshold as a function of the maximum flow rate of the channel.

If we consider that the variation of flow on a given network is 50%, the threshold BSS can be calculated as follows: BSS = (UBSB - ((BitRateMoy * 1 .5) * durationBitRateMax)) / BitRateMoy

BSS = (UBSB - (BitRateMax * durationBitRateMax)) / BitRateMoy

Figures 6a and 6b described above illustrate this variant. The steps G3 (respectively G'3) to G5 are then inserted before or after the steps S3 and S4.

According to a second variant related to the reduction of bit rate, a bit rate reduction can be applied by recording only certain parts of the data. Figures 7a and 7b illustrate such a variant. Steps A2 (respectively A'2) to A4 are then inserted before or after steps S3 and S4.

According to a third variant related to the reduction of the rate, the microprocessor 33 only records part of the data groups received. When the data conforms to the MPEG coding standards, for example MPEG-2 or MPEG-4, the data is encoded in the form of image groups known by the acronym GOP (acronym for "group of pictures").

Figures 8a and 8b illustrate this embodiment. The steps H2 (respectively H'2) and H3 are then inserted before or after the steps S3 and S4. Figure 3 previously described also represents a particular embodiment of this invention.

We will now describe the specifics of the fifth invention.

The method according to the fifth invention consists in performing the steps of FIG. 6a or 6b.

According to a preferred embodiment, this fifth invention relates to a device for receiving and recording audio video data on a recording medium, the device comprising a processor for implementing a time shift function in a part of said recording medium called memory. time shift buffer. According to the invention, the processor includes means for transcoding the received data to reduce the amount of data to be recorded before recording in the time shift buffer.

Advantageously, an additional rate reduction can be applied by recording only certain portions of the data. Figures 7a and 7b, previously described illustrate such a variant. This additional rate reduction can be done before or after the transcoding rate reduction.

Advantageously, an additional rate reduction can be applied by recording only certain groups of data. Figures 8a and 8b described above, illustrate such a variant. This additional rate reduction can be done before or after the transcoding rate reduction.

FIG. 3, previously described, describes a management with two thresholds of the temporal shift buffer applicable following the transcoding of the data according to FIGS. 6a or 6b and according to the variants previously described.

FIG. 9 describes a management with 4 thresholds of the temporal shift buffer applicable following the transcoding of the data according to FIGS. 6a or 6b and according to the variants previously described. FIGS. 10 and 11 describe two first variants of the embodiment described in FIGS. 3 and 9.

In these two variants, intermediate steps between steps T1 and T2 of FIG. 9 or E1 and E2 of FIG. 3 make it possible to parameterize the three thresholds BSS, BSB and MBSS as a function of the type of data received.

- audio (a radio service for example),

- HD video, (an HD TV service for example),

the SD video, (an SD TV service for example),

One can also consider an HD audio service and an SD audio service.

During a test V1 between steps T1 and T2, that is to say when receiving data, following a change of string, the processor 33 determines the type of data received. This type can be determined for example by reading header fields or metadata. In the case of MPEG-2 or MPEG-4 coded data, the PMT tables detect such a type of data. If the data is audio data then the three thresholds are set with the following thresholds during a step V4:

BSS = BSS_aud

BSB = BSB_aud

MBSS = MBSS_aud

The audio data rate is low compared to the video data rate, whether SD or HD.

If the data is not audio data, then in a step V2, the processor tests whether the data is SD video data. If the data is SD video data, then the three thresholds are set with the following thresholds during a step V5:

BSS = BSS_SD

BSB = BSB_SD

MBSS = MBSS_SD

If the data is not SD video data, then in a step V3, the processor tests whether the data is HD video data. Yes the data is HD video data, then the three thresholds are set with the following thresholds during a step V6:

BSS_HD BSS =

BSB = BSB_HD

MBSS = MBSS_HD

Following the parameterization of the thresholds, we then go to step T2.

During a test W1 between steps T1 and T2, that is to say when receiving the data, following a change of chain, the processor 33 determines the type of data received. This type can be determined for example by reading header fields or metadata. In the case of data coded in MPEG-2 or MPEG-4 (H264) format, the PMT tables make it possible to detect such a type of data. If the data is H264 data then the three thresholds are set with the following thresholds during a step V4:

BSS_HD BSS =

BSB = BSB_HD

MBSS = MBSS_HD

BSS = BSS_SD

BSB = BSB_SD

MBSS = MBSS_SD

BSS = BSS_X

BSB = BSB X MBSS = MBSS_X

Following steps W4, W5 or W6, the processor proceeds to step T2, if it came from T1 or E2 if it came from E1.

Figure 12, described above, represents a variant of the invention. In this second variant, intermediate steps between the steps T1 and T2 of FIG. 7 or E1 and E2 of FIG. 6 make it possible to parameterize the three thresholds BSS, BSB and MBSS as a function of the bit rate of the received data.

We will now describe the specifics of the sixth invention. The method according to the sixth invention consists in performing the steps of FIG. 7a or 7b.

According to a preferred embodiment, this sixth invention relates to a device for receiving and recording audio video data on a recording medium, the device comprising a processor for implementing a time shift function in a part of said recording medium called memory time shift buffer, the data being encoded in a plurality of modes, the modes being relative to an audio language or subtitling. According to this sixth invention, the processor comprises

Means for detecting the mode in which the data is decoded,

- Means for recording in the time shift buffer memory, the data only in the only decoded mode. According to a variant related to the reduction of the rate, the microprocessor 33 only records part of the data groups received. When the data conforms to the MPEG coding standards, for example MPEG-2 or MPEG-4, the data is encoded in the form of image groups known by the acronym GOP (acronym for "group of pictures").

Figures 8a and 8b illustrate this embodiment. This additional rate reduction can be performed before or after the rate reduction related to the decoded mode.

An additional bit rate reduction can be applied by transcoding the received data. FIGS. 6a and 6b previously described illustrate this embodiment. This additional rate reduction can be performed before or after the rate reduction related to the decoded mode.

FIG. 3, previously described, describes a management with two thresholds of the buffer of temporal shift applicable following the reduciton of flow applied to the data according to FIGS. 7a or 7b and according to the variants described previously.

FIG. 9 describes a management with 4 thresholds of the temporal shift buffer applicable as a result of the rate reduction applied to the data according to FIGS. 7a or 7b and according to the variants previously described.

FIGS. 10 and 11 describe two first variants of the embodiment described in FIGS. 3 and 9.

We will now describe the specifics of the seventh invention.

The method according to the seventh invention consists in performing the steps of FIG. 8a or 8b.

According to a preferred embodiment, the present invention relates to a device for receiving and recording data on a recording medium, the device comprising a processor for implementing a time shift function in a part of said recording medium called a buffer memory. time offset, the data being audio video data encoded into video data groups and audio data group. According to this invention, the device comprises means for recording in the memory only a percentage less than the totality of the groups of video data received and all the groups of audio data. Advantageously, an additional rate reduction can be applied by recording only certain portions of the data. Figures 7a and 7b, previously described illustrate such a variant. This additional rate reduction can be performed before or after the rate reduction related to the decoded mode.

Advantageously, an additional additional bit rate reduction can be applied by transcoding the received data. Figures 6a and 6b previously described illustrate this embodiment. This additional rate reduction can be performed before or after the rate reduction related to the decoded mode.

In these two variants, intermediate steps between the steps T1 and T2 of FIG. 9 or E1 and E2 of FIG. 9 make it possible to parameterize the three thresholds BSS, BSB and MBSS as a function of the type of data received.

Claims

claims

A device for receiving and recording data on a recording medium, the apparatus comprising a processor for implementing a time shift function in a part of said recording medium called a time shift buffer, characterized in that it comprises

Means for defining a first threshold (BSB) defining a capacity limit of the time shift buffer memory and

Means for defining a second threshold (BSS) defining a limit in recording time in the time shift buffer memory and

the processor stores the data in the time shift buffer memory until the second threshold is reached and when the second threshold is reached before the first threshold, the processor truncates the start of the time shift buffer memory when the data during playback are not located at the beginning of the buffer or replay reads data from the time shift buffer when the data being read is located at the beginning of the time shift buffer.

Device according to Claim 1, characterized in that the processor comprises

means for adjusting the second threshold (BSS) according to said at least average bit rate.

Device according to Claim 2, characterized in that the means for analyzing the average flow rate also analyze the maximum flow rate of each channel, the means for adjusting the limit in recording time then adjusting the limit according to said average flow rate and the maximum flow rate of each channel.

4. Device according to claim 1 characterized in that the recording time limit is adjusted for each channel according to its average rate.

5. Device according to claim 2 characterized in that the capacity is adjusted for each channel according to its average flow rate and its maximum flow.

6. Device according to claim 1 characterized in that the processor comprises

means for analyzing the type of data received,

means for adjusting the second threshold (BSS) according to the type of data received.

7. Device according to claim 6 characterized in that the type comprises:

- audio data,

- standard definition video data,

- High definition video data.

8. Device according to one of the preceding claims characterized in that the processor comprises

Means for detecting a filling threshold of the buffer memory.

9. Device according to claim 8 characterized in that the processor comprises means for transcribing the data received when the filling threshold is crossed.

10. Device according to one of the preceding claims characterized in that the processor comprises means for detecting the type of data received.

1 1. Device according to claim 1 0 characterized in that the processor comprises

Means for transcoding the data received when the data type corresponds to data of the high-speed type.

1 2. Device according to one of the preceding claims and claim 8 characterized in that the processor comprises

Means for recording in the temporal shift buffer memory only the detected data. 3. Device according to one of claims 1 to 1 1 and claim 1 0 characterized in that the processor comprises

Means for detecting the data relating to the language displayed by the user or to the subtitling viewed by the user,

Means for recording in the time shift buffer only the data detected when the data type corresponds to data of the high-speed type.

14. Device according to one of claims 1 to 1 3 and claim 8 characterized in that the processor comprises means for recording in the time shift buffer memory only a percentage less than all the groups of data received when said Received data is encoded into a data group when the fill threshold is crossed.

15. Device according to one of claims 1 to 13 and claim 10 characterized in that the processor comprises means for recording in the time shift buffer memory only a percentage less than the totality of the groups of data received when said data received are coded in a data group when the data type corresponds to data of the broadband type.

A method of receiving and recording data on a recording medium, in a device comprising a processor for implementing a time shift function in a part of said recording medium called a time shift buffer, characterized in that the method comprises:

Determining a first threshold (BSB) defining a capacity limit of the time shift buffer memory and

Determining a second threshold (BSS) defining a limit in recording time in the time shift buffer memory and

- The recording of the data in the time shift buffer memory until the second threshold is reached and

when the second threshold is reached before the first threshold, truncating the start of the time shift buffer memory when the data being read is not located at the beginning of the buffer memory or

- Switching read data of the time shift buffer memory when the data being read is located at the beginning of the time shift buffer.